I was recently asked how long the demo I have created in XD will be stored (and available) on adobe.com by clicking the link I have created. The link will be passed to a client so they can comment on the design so I am sure it will be accessed by many different people and the same link maybe updated as feedback is factored in.
You as the designer actually control how long the link is up and available. By default, the link is always available, but you can then modify it afterward to either update with new content or new permissions. You can delete the published content if you want by clicking on "Manage Links." Hope that helps!